The present invention is directed to a one way valve assembly for dispensing a sterile flowable substance while preventing any backflow of contaminants into the source of the flowable substance. The valve assembly includes a valve body enclosed by a pressure displaceable flexible member or elastomeric member for effecting the passage of the flowable substance to a controllable outlet while preventing any backflow to the source of the flowable substance after dispensing individual portions of the flowable substance.
In the past, to maintain the flowable substance free of contaminants, preservatives have been mixed in the flowable substance in the container from which it is to be dispensed. The use of preservatives is an added expense and tends to limit the effectiveness of the flowable substance, particularly when the flowable substance is a pharmaceutical such as an eye care solution or it is a food stuff.
Another consideration is the ability of the valve assembly to deliver a selected amount to the outlet without causing any damage to the user, such as when applying an eye care solution directly into the eye.
In recent years, flexible membranes have been used to control the flow of the flowable substance to the valve assembly outlet while preventing any backflow to the source of the flowable substance, however, it has been difficult to provide an effective procedure for manufacturing the valve assembly and limiting its costs.